Thioformaldehyde and mercuric chloride treatment of protein filaments



x a concentrated aqueous solution of Patented Oct. 14, 1952 TIilOFOBMALDEHY summon-mama .iilL M ia.

Great Britain No Drawing.

rial Not 74,324. In

'7 Claims. 1

The; present invention .is concerned with. the provision of a method for improving the-strength of: artificial. protein filaments treated; with reagents;;capable of formingin. situi'nascent monomericr'thioformaldehyde as for example, accordingto United States Patent N=;Z,3l9,009so as to topermit them to be readily I processed. irrrthe existing machinery employedinv the manufacture of textile products.

United States Patent No. 2,319,009 describes and claimsinter alia the treatment of coagulated casein or vegetable seed protein filaments with a salt of a hydroh'alide contai "ng" formaldehyde, or a compound whichwill yield formaldehyde under the conditions of the treatment; a-salt of areducing sulphur-"acid in" which th'eatomic --proportion, reckoned on theanhydrous salt, of -oxygen if present, to sulphur does not exceed 2:1,- and an acid which does not oxidize the salt of the sulphur acid; and which is substantially completedilute aqueous solution.

While it is known that stretching of coagulated wet spun filaments previous to their insolubilisation, for example by means of formaldehyde in the presence of an acidified highly concentrated aqueous saline solution, has a beneficial effect on the strength of the insolubilized filaments produced, and that the strength of the insolubilized filaments, can frequently be further increased by treatments involving further stretching, such stretching processes as have heretofore been disclosed with respect to protein fibers not only do not permit the application of extensive stretching but the effects produced are only relatively small.

In our copending application Serial No. 45,794, filed August 23, 1948, now Patent 2,535,103, we have described a method for improving the strength of artificial protein filaments which have been insolublized by treatment with formaldehyde by treating these insolubilized filaments while under tension in an aqueous solution of an ionizable mercuric sal We have now found that filaments of very marked improved strength are obtained if coagulated protein filaments treated according to United States Patent No. 2,319,009, if desired washed to free them from surface and uncombined acid or formaldehyde, are treated under tension with an aqueous solution containing mercuric chloride.

According to the method of ficial protein ly ionized in the present invention, therefore, improving the strength of artifilaments treated with reagents DE3Z AND. MEacnmd MENT- on-rnoram Fairlie, and David Traill,

Scotland, assignorsto Imperial Chemical Industries Limited;

acorporation f:

Application February .4', 1949,' Se-- Great Britain March 3; 1948" States Patent No.

capable of forming-:in situnascent monomeric thioformaldehyde as for example vaccordingrto United States Patent No. 2,319,009: comprises treating the said protein filaments under tension with an aqueous solution of mercuricrchloride;

The aqueous solution of mercurics..chloride'-' is preferably at a temperature betweena'll)? C. and C. and is preferably acidified with hydrochloric acid.

The protein filaments. treatedi accordi'nge to United StatesPatent: No. 2,319,009: arelpreferably stretched to about .350 per cent'whilesundergoing treatment in an-aqueoususolution of mercuric chloride.

The treatment according to the invention: can reduce the diameter of the filaments;by=aboutz9p and can increase the .wetstrength of the: .fiiazment by about '60 per cent. i

Protein filaments: treated according to: United 2,319,009 tendtozhave low elongation at break in the: dry state fandhigh :elon'ga tion when wet. Treatment accordingto the present invention improves these properties, that is to say the fibres become less brittle when dry and less plastic when wet.

The invention is illustrated by the following example.

A solution of ground nut protein in caustic soda is extruded into a sulphuric acid/sodium sulphate coagulating bath. These fibres are now given an insolubilizing treatment for 16 hours at 38 C. in a solution consisting of 960 m1. brine. 30 ml. formalin, 40 ml. conc. hydrochloric acid and 32.5 gm. sodium sulphide (NazS.9HzO). The fibres are now washed free from acid and dried at C. The insolubilized tow thus obtained is now stretched to a maximum in a bath containing 3% mercuric chloride and 0.1 N hydrochloric acid at 70 C. The stretch is maintained for about 30 minutes and the tow is then washed in running water and dried at 08 C.

The sulphide-insolubilized filaments treated with mercuric chloride in this manner are increased in wet strength to about 60 per cent and the increaseof elongation at break when dry is about 200 per cent. The elongation at break when wet is decreased by 50 per cent.

It will be appreciated that the term insolubilized, as used in the appended claims, is intended to mean filaments which have been treated with thioformaldehyde so as to be substantially unaffected when exposed to the resistance test outlined on page 2, column 2, lines 55 through 61, of U. S. Patent No. 2,319,009, i. e., the filaments should be substantially unaffected by 3 treatment for 90 minutes at 97 0. with a bath containing 0.1% sulfuric acid and 0.25% sodium sulfate. The filaments being treated are, therefore, to be distinguished from hardened portein filaments, i. e., filaments which are insoluble in cold water but are affected adversely in boiling water and hot dilute acid. In other words, the insolubilized protein filaments with which the present application is concerned are not only insoluble in cold water, but are also resistant to boiling water and hot dilute acid.

We claim:

1. A method of improving the strength of artificial protein filaments selected from the group consisting of casein and vegetable seed protein filaments which have been insolubilized by treatment with nascent monomeric thioformaldehyde formed in situ which comprises stretching said insolubilized protein filaments while in an aqueous solution of mercuric chloride under conditions sufiicient to effect a substantial increase in the wet strength and dry elongation at break of said filaments.

2. The method of claim 1, wherein the aqueous solution of mercuric chloride is at a temperature of between 70 and 80 C.

3. The method of claim 1, wherein the aqueous solution of mercuric chloride is acidified with hydrochloric acid.

4. The method of claim 1, wherein the insolubilized protein filaments are stretched to about 350% of their original length, while in the aqueous solution of mercuric chloride.

5. A method of improving the strength of artificial protein filaments selected from' the group consisiting of casein and vegetable seed protein filaments which have been insolubilized by treatment with nascent monomeric thioformaldehyde formed in situ which comprises stretching said insolubilized protein filaments to about 350% of their original length in an aqueous solution of mercuric chloride and hydrochloric acid GEORGE K. SIlVLPSON. DAVID TRAILL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 339,348 Tweedy Apr. 6, 1886 998,341 Illingsworth July 18, 1911 1,799,047 Jones Mar. 31, 1931 2,297,397 Ferettl Mar. 2, 1940 2,319,009 McLean May 11, 1943 2,374,201 Highberger et al. Apr. 24, 1945 FOREIGN PATENTS Number Country Date 508,781 Great Britain June 26, 1939 OTHER REFERENCES Synthetic Tannins, G. Grasser and Enna, Crosby Lockwood and Son, London (1922), page 75.

A Study on Chronic Mercurialism in the Hatters Fur-Cutting Industry, page 38 of Public Health Bulletin Number 234, U. S. Public Health Service.

News Edition-Amer. Chem. Soc., November 5, 12941, article by Beal et al. Pages 1239 and 1242. 

1. A METHOD OF IMPROVING THE STRENGTH OF ARTIFICIAL PROTEIN FILAMENTS SELECTED FROM THE GROUP CONSISTING OF CASEIN AND VEGETABLE SEED PROTEIN FILAMENTS WHICH HAVE BEEN INSOLUBILIZED BY TREATMENT WITH NASCENT MONOMERIC THIOFORNALDEHYDE FORMED IN SITU WHICH COMPRISES STRETCHING SAID INSOLUBILIZED PROTEIN FILAMENTS WHILE IN AN AQUEOUS SOLUTION OF MERCURIC CHLORIDE UNDER CONDITIONS SUFFICIENT TO EFFECT A SUBSTANTIAL INCREASE IN THE WET STRENGTH AND DRY ELONGATION AT BREAK OF SAID FILAMENTS. 